AP Biology unit 3

What work in cells requires energy

Chemical, transport, and mechanical

Chemical work example

Protein synthesis

Transport work example

Transporting molecules against its concentration gradient

Mechanical work example

Muscle contraction

Exergonic Reaction

Releases free energy, negative energy change

Endergonic Reaction

Absorbs free energy, positive energy charge

Coupled reactions

When the energy released in exergonic reactions is used as the input for endergonic ones. 

Coupled reactions example

ATP hydrolysis, photosynthesis

ATP hydrolysis

The enzyme ATPase breaks the high-energy phosphate bond in ATP to convert it to ADP, which releases energy.

Enzyme

A biological catalyst that speeds up chemical reactions by lowering the activation energy required for the reaction to occur.

Substrate

Specific molecule

Active site

Part of the enzyme the substrate binds to.

Enzymes-Low temperature effect

Slows reaction rate due to less kinetic energy and therefore less collisions between enzymes and substrates.

Enzymes-Optimal temperature

For many humans it is 37, increases the reaction rate as kinetic energy increases.

Enzymes-High temperatue

Causes enzyme to denature, losing its specific 3D shape, which makes it inactive. The reaction rate then drops sharply. 

Enzymes-Optimum pH

Range where the enzyme functions efficiently and is in its correct structural state. 

Enzymes-deviations from optimum pH

As pH moves from optimum(acidic or alkaline), enzyme activity decreases because the shape of the enzyme begins to change. 

Enzymes-drastic deviation from pH

Denaturation can occur because drastic pH changes causes the enzyme to unfold,changing its active site’s structure. 

Enzymes-low substrate concentration

As substrate concentration increases from low concentration, reaction rate will increase

Enzymes-rising substrate concentration

The reaction rate levels out when all enzyme active sites are saturated, increases have no effect. 

Enzymes-product concentration increase

As product concentration increases, reaction rates can slow because the product can bind to the enzymes active site and compete.

competitive inhibitors

competes with substrate due to similar shape. If substrate concentration is high enough, it can outcompete the inhibitor.

Noncompetitive inhibitor

Binds to the allosteric site. the binding changes the shape of the active site and the substrate cannot bind correctly. 

Cellular Respiration equation

C6H12O6+6O2=6CO2+6H2O+energy

Glycolysis location

Cytoplasm

Glycolysis

Glucose is broken down into pyruvate and ATP, electrons picked up by NAD

Glycolysis inputs

Glucose, NAD, ATP, ADP

Glycolysis outputs

Pyruvate, NADH, ADP, ATP, H2O

Pyruvate Oxidation location

Mitochondrial matrix 

Pyruvate oxidation

Pyruvate from glycolysis is oxidized into Acetyl-CoA

Pyruvate oxidation input

Pyruvate, NAD+,

Pyruvate oxidation output

Acetyl-CoA, NADH, CO2

Krebs Cycle location

Mitochondrial matrix

Krebs cycle inputs

Acetyl-CoA, NAD, FAD, ADP, Pi

Krebs cycle outputs

NADH, FADH2, ATP, H2O

ETC location eukaryote

Inner mitochondrial membrane

ETC location prokaryote

Cytoplasmic membrane

Electron Transport Chain(CR)

Series of proteins embedded in membrane pass along electrons through series of chemical reactions. The energy from the passing allows for the proton pump to establish an electrochemical gradient. O2 is the last acceptor of electrons, forms water as a byproduct. 

Electron Transport Chain(CR) input

NADH, FADH2, ADP, O2

Electron Transport Chain(CR) output

NAD, FAD, ATP, H2O

Oxidative Phosphorylation

ATP synthase is a molecular machine that generates ATP from the energy from chemiosmosis through the protein. Involves ETC and ATP synthase

ATP Synthase

Molecular machine that generates ATP with energy from Chemiosmosis by synthesizing ADP and inorganic Phosphate. 

Chemiosmosis

Flow of protons down an electrochemical gradient. Generates energy. 

Fermentation

Allows glycolysis to continue without oxygen by regenerating NAD+ from NADH and transferring the electrons to pyruvate, which results in byproducs(lactic acid or ethanol)

Photosynthesis equation

6CO2+6H2O+light energy=C6H12O6+6O2

Light reaction location

Thylakoid

light reaction inputs

light+water+ADP+NADP

Light reaction outputs

O2, ATP, NADPH

Light reaction

Captures light with pigments called chlorophylls. Light excitesthe electrons in photosystem II, and the electrons pass along the ETC. Photosystem two oxidizes the water to replenish electrons, which results in Oxygen. Electrons are reexcited in photosystem I, which converts NADP to NADPH. The electrochemical gradient and chemiosmosis drives ATP synthase to produce ATP. 

Final electron acceptor of light reaction

NADPH

Calvin Cycle location

Stroma

Calvin cycle inputs

CO2, ATP, NADPH

Calvin cycle outputs

Glucose, NADP, ADP

Calvin cycle

Enzyme catalyzed reactions convert CO2 to organic carbs.

First to photosynthesize

Prokaryote cyanobacteria 3 billion years ago

The great oxygenation event

Oxygen produced by prokaryotes built up in the atmosphere, led to anaerobic mass extiction but developed aerobic respiration. Fac

Photosynthesis light intensity

Light intensity increases the rate, when graph levels off it is due to another limiting factor

Photosynthesis CO2 concentration

At lower CO2 concentrations, it is a limiting factor, until enzymes are saturated or other limiting facotr, rapid increase then plateau. 

Photosynthesis Temperature

Photosynthesis is an enzymatic reaction, so temperature affects it. As temperature increases, enzyme activity increases because of increased kinetic energy, but too much and the enzymesd can denature, leading to a drop in the rate. Graph is a bell curve. 

Photosystem II

First to capture light energy, splits water molecules, releases O2, protons, and electrons 

Photosystem I

Reenergizes electrons, uses them to produce NADPH, which carries energy to the calvin cycle.

Calvin Cycle steps 

Carbon fixation, reductions, RuBP regeneration

Carbon fixation 

enzyme RuBisCO attatches CO2 to RuBP, which splits to 3PGA

Reduction

3PGA is reduced to PGAl, 6 produced, 5 remain in cycle

RuBP regeneration

remaining 5PGAL regenerate RuBP

Photosynthesis electron carrier

NADPH

Cellular respiration electron carriers

FADH2, NADH

Anabolic pathways

Synthesizes smaller molecules into bigger ones, endergonic reaction because it requires energy.

Catabolic pathways

Breaks down bigger molecules into smaller ones, exergonic because it releases energy.

Anabolic pathway example

photosynthesis

Catabolic pathway example

cellular respiration